A few more updates to the Washington, USA map module as well as updates on the new multi-thread navigation code.

Build #623 on LOGistICAL 2- New navigation fixes to stop all trucks obeying the rules of 1st or last truck- ability to zoom in a bit more- yellowed the region borders- blued the rivers- show rivers when scrolling around

Build #622 on LOGistICAL 2- Fixed new navigation problem with only one truck takes the route with a multi-select- Fixed problem with trucks of a multi-select are already at the destination and others aren't- Fixed cake problem in the Poulsbo area of USWA- "HELP keys" now shows up center screen- Upgraded road section at Dollar Corner, USWA- Upgraded road section near Spokane, USWA- Removed resource from Brady, USWA- Added padlocks to locked towns for dragging cargo- Fixed a missing road segment- Fixed sections where large trucks can't get out of- Removed lines of the "module completion" section that gave maths errors due to zero towns or trucks